Siegfried marasse



UNrTED STATES PATENT union.

SIEGFRIED MARASSE, OF BERLIN, GERMANY.

PROCESS OF MAKING SALICYLIC A-CID.

SPECIFICATION forming part of Letters Patent No 529,182, dated November13, 1894.

Application filed April 25,1894:- Serial No. 508,985. (No specimens.)Patentedin Germany February 20,1893,No. 73.279: iii France August 23,1893, No. 232,352, and in England September 9, 1893, No. 17,002.

To all whom it may concern.-

Be it known that I, SIEGFRIED MARASSE, a subject of the King of Prussiaand German Emperor, residing in the city of Berlin, in Prussia, Germany,have invented certain new and useful Improvements in Processes of MakingSalicylic Acid, (for which Letters Patent were granted to me in Germany,No. 73,279, dated February 2O, 1893; in France, No. 232,352, datedAugust 23, 1893, and in Great Britain, No. 17,002, dated September 9,1893,) of which the following is aspecification.

In the processes heretofore used for making salicylic acid on a largecommercial scale, it is obtained from phenolates of the alkalies oralkaline earths. These phenolates have to be absolutely free of water,which requires a tedious treatment, previous to subjecting them to theaction of carbonic acid gas in open or closed vessels at a graduallyincreasing temperature. On the other hand, according to an experimentpublished by Drechsel in the Zeitschrzlft fi'lr Ohem'ie for the year1865, page 580, salicylic acid is found to generate slowly and in smallquantities, when a mixture of phenol, potassium bicarbonate (KHCO andwater is placed in a glass-tube, which is then sealed by melting and inwhich said mixture is kept for several days at a temperature of 160centigrade. Moreover, from experiments made by Senkofer, Brunner andSarlay, published in the Wiener Academz'sche Berichte volume 80, pages504 to 524, and volume 84, pages 323 and 331, it appears that whenphenols containing morethan one atom of oxygen are heated for fourteenhours with ammonium carbonate and potassium bicarbonate in an aqueoussolution, the monoor dicarboxilic acid of the respective phenol isproduced. No such action, however, takes place on the phenol itself, C HOH. These investigators emphasize repeatedly the fact that from phenolproper, under the action of ammonium carbonate and water, they alwaysobtained only traces of salicylic acid. Consequently, owing to theseextremely unsatisfactory results, neither the process described byDrechsel, nor that of Senkofer, Brunner and Sarlay, can be used on alarge scale for manufacturing the most important of the aromaticoxycarbo-acids, known as salicylic acid.

The object of my invention is to furnish a process by which a completereaction is obtained without the necessity of producing and drying thephenolates; and the invention consists of the process of makingsalicylic acid by subjecting a dry mixture of phenol with neutralpotassium carbonate or potashes in excess to the action of carbonic acidgas at a gradually increased temperature, as will be fully describedhereinafterandfinallypointed out in the claims.

, carbonate, and subjected in a closed receptacle to the action of therequired quantity of carbonic acid gas at a graduallyincreasedtemperature. The best temperature is between 130 and 160 centigrade. Itis especially important that an excess of potassium carbonate be used,so as to prevent the mixture fromcaking when heated, as thereby thecarbonic acid gas would be prevented from entering freely either whollyor in part, into the mix- 5 ture and acting on the same. As soon as thetion is reached, the carbonic acid gas will act readily and instantly,as can be observed on the pressure gage. When, after cooling, thereceptacle is opened, it will be found that the ,phenol has beenconverted almost completely into potassium salicylate. The reaction, inwhich apparently no intermediate products are formed, takes placeaccording to the following equation:

under separation of water, as appears from the temperature mostadvantageous for the reac" In carrying out my improved process, phe- Vnol is intimately mixed with neutral potasslum equation representing thereaction. The process even permits some water to be added or to bepresent in the reagents without preventing the formation of salicylicacid, provided always that a sufficient quantity of potash is present toprevent the mixture from caking or solidifying. In the processeshereinbefore described, the presence of water has to be carefullyavoided.

Second. It was observed and stated by Baumann, (Berichte der DeutschenChemischen Gesellschaft, volume 10, page 686,) that on boiling phenolfor fourteen hours with a so lution of potash under development ofcarbonic acid, potassium phenolate will be formed. It might therefore bepresumed that in my before-described process the formation of potassiumphenolate would precede the generation of salicylic acid. That this isnot the case and that in a closed receptacle, the reaction observed byBaumann does not take place, is proved by the following experiment: Whenpotassium phenolate is subjected in a closed vessel in the presence ofwater to the action of a small quantity of carbonic acid, phenol will beset free and potassium carbonate formed. This separation occurs at loweras well as at higher temperatures. In my improved process, in whichwater is generated, potassium carbonate comes without the least doubtinto simultaneous action with the carbonic acid. The ready formation ofsalicylic acid is mainly based upon the joint and simultaneous action ofthe potash and carbonic acid on the dry porous mixture of the phenol andpotash.

Third. A further important feature of my improved process is theintimate mixture of the phenol with potash, the latter being added inexcess to such an extent that the mixture, even at a higher temperature,is retained in the form of a dry powder, so that it can be easilypenetrated and attacked in all its parts by the carbonic acid gas. Thisdry porous intimate mixture of the ingredients is a preliminarycondition for the reaction and the complete conversion of the phenolinto salicylic acid. This fact also distinguishes my new process fromthat ofDrechsel, where likewise after heating are present potash,phenol, water and carbonic acid, but independently of each other. Thecarbonic acid gas, however, is not confronted by a loose porous mixture,but is in the presence of two superposed liquids which do not penetrateeach other, the one being an aqueous, the other an oily substance, whichprevents them from acting one upon the other. The oily liquid separatesthe carbonic acid from the aqueous liquid, and though the heating becontinued for days, the carbonic acid will only generate a very smallamount of salicylic acid. Consequently, no useful result is obtained inthis instance, while by my improved process, a very advantageous processis obtained, that can be carried out on a large scale and which yields ahigh percentage of salicylic acid.

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1, The process herein-described of making salicylicacid, which consists in subjecting a dry mixture of phenol and potassiumcarbonate in excess to the action of heat and carbonic acid gas underpressure until the reaction is completed and potassium salicylateobtained, and then producing salicylic acid from the potassiumsalicylate in the wellknown manner, substantially as set forth.

2. In the process of making salicylic acid, the step of producingpotassium salicylate by subjecting a dry mixture of phenol and potassiumcarbonate in excess to the action of heat and carbonic acid gas underpressure, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two subscribing witnesses.

SIEGFRIED MARASSE.

Witnesses:

PAUL EBERTY, GUISAR ZEIKER.

